Engine & Internal Chat about beefing up your Blazer's engine insides here.

How much cfm do I really need?

  #1  
Old 03-23-2016, 02:38 AM
error_401's Avatar
Moderator
Thread Starter
Join Date: Nov 2007
Location: Zurich
Posts: 1,114
error_401 is on a distinguished road
Default How much cfm do I really need?

In the middle of rebuilding I'm stuck with some basics.

The heads of the 1994 blazers seem to suck at some 135 cfm.

When plugging in a couple of figures to try to get a hold of what cfm numbers are really required for a specific power output I'm getting to flows in the 75 - 85 cfm (theoretical) for a 250 - 275 hp 4.3l V6 (262 cid).
That would mean:
- the OEM heads would be perfectly fine to make that hp.
- at least half of the tuning for cfm on the heads is overkill.

I'm aware of the following:
- a high average airflow at half lift makes most power and especially torque
- the time is the restricting factor on a valvetrain but I'm aiming at around 3'000 - 3'250 rpm for peak torque
- even at 135 cfm below the opening curve of the valvetrain I should be able to get to an average of 75 cfm.

Is there somebody which can point me to the right sources of wisdom as to required cfm per cylinder?
Anybody ever tuned a 4.3l and what were the figures?

I guess that for serious hp I would need a head like BRODIX -6's or swap a 1996 or later kidney bean combustion chamber head on.
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Blade_24k
2nd Gen S-series (1995-2005) Tech
4
10-25-2013 04:26 AM
serrasalmus
The Lounge
3
06-12-2012 05:57 PM
IrvJr
General Chat
4
05-07-2012 07:48 AM
Spectreblazer
Full Size K5 (1969-1991) GMT415 (1992-1994) Tech
3
03-15-2010 11:16 PM
88s10Blazer
1st Gen S-series (1983-1994) Tech
7
11-29-2006 02:56 AM


Thread Tools
Search this Thread
Quick Reply: How much cfm do I really need?


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.